<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var xhr = new XMLHttpRequest();
        xhr.onreadystatechange = function () {
            console.log(xhr.readyState);
        }
        xhr.open('GET', 'http://bufantec.com/api/test/user/list');
        xhr.send(null);
    </script>
</body>
</html>